Telephone Signaling tones

[NatureBoy]

Hi, I'm trying to find the best and simplest method of generating telephone signaling tones such as dial and busy tones.
Does anyone have any schematics.

 

[DigiTan]

Well, if you ask me, I'd say the easiest way of producing those signals is through an IC and a microcontroller. I guess I don't have any schematics but if you're interested in components, I bought some DTMF chips from **broken link removed** a while ago that seemed to work very well (didn't test them extensively). If your interested call progress tones though, I'd try out their **broken link removed** generator [link has .pdf], which is availible in DIP14 or SOIC16.

As far as dialing goes, I'd try thier M-8888 (8051 and i86 interfaceable), or M-8880 (for Motorola-type interfacing). Both chips were very reliable, and --if I remember right-- they even took care of that 3db "twist" between the tone pairs. Most of those parts are availible through Digikey.com. I also found some very useful diagrams for phone interfacing at this Helsinki University of Technology site.

 

[chemelec]

The Simplest way is to buy a Tone Generator IC.

An MC14410P is one such chip to generate these tones.
An MC567 is a decoder chip for these tones

 

[NatureBoy]

Hey thanx alot. I will look into using that tone generator I.C that you mentioned. However, I did use 2 555 timers in the astable configuration to generate the individual tones and then used a LM381 chip configured as a mixer to mix both tones. After which I coupled the output of the mixer through a capacitor and sent it to a speaker.

The dial tone generated sounds like a dial tone, however it has a higher pitch.
I'm not really satisfied 100% with the results, so I will try your suggestion if I can source that chip.

Thanx alot.